title: Calcium-induced membrane microdomains trigger plant phospholipase D activity.
abstract: Plant alpha-type phospholipase D proteins are calcium-dependent, lipolytic enzymes. The morphology of the aggregates of their phospholipid substrate fundamentally defines the interaction between the enzyme and the surface. Here we demonstrate that the Ca(2+)-induced generation of membrane microdomains dramatically activates alpha-type phospholipase D from white cabbage. 500-fold stimulation was observed upon incorporation of 10 mol % 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphate (POPA) into 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) vesicles in the presence of Ca(2+) ions. Enhanced association of PLDalpha2 with phospholipid surfaces containing anionic components was indicated by lag phase analysis and film balance measurements. Differential scanning calorimetry showed that the POPA-specific activation correlates with the phase behavior of the POPC/POPA vesicles in the presence of Ca(2+) ions. We conclude from the results that the Ca(2+)-induced formation of POPA microdomains is the crucial parameter that facilitates the binding of PLD to the phospholipid surface and suggest that this effect serves as a cellular switch for controlling PLD activity.
authors.affiliation: Institute of Biochemistry and Biotechnology, Martin-Luther University Halle-Wittenberg, Kurt-Mothes Strasse 3, 06120 Halle, Germany.
authors.forename: Konstantin
authors.initials: K
authors.lastname: Kuppe
authors.forename: Andreas
authors.initials: A
authors.lastname: Kerth
authors.forename: Alfred
authors.initials: A
authors.lastname: Blume
authors.forename: Renate
authors.initials: R
authors.lastname: Ulbrich-Hofmann
mesh_terms: D001937:Brassica / Q000201:enzymology*; D002122:Calcium Chloride / Q000494:pharmacology*; D002152:Calorimetry, Differential Scanning; D008563:Membrane Lipids / Q000737:chemistry*; D021962:Membrane Microdomains / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D044367:Phase Transition; D010739:Phospholipase D / Q000737:chemistry / Q000378:metabolism
chemical_list: D008563:Membrane Lipids; D010739:Phospholipase D; D002122:Calcium Chloride